Astrocytes release a number of gliotransmitters which modulate the function and excitability of associated neurons. These include ATP and its derivative adenosine which act to depress neuronal activity. Increases in astrocytic intracellular calcium can be used as an indication of phospholipase C activity and ATP release. Preliminary evidence indicates that status epilepticus (SE) results in a prolonged increase in calcium excitability in cortical astrocytes that is temporally correlated with SE-induced neuronal death. I will use two-photon microscopy to ask if astrocytic calcium oscillations and wave propagation in the hippocampus are affected by SE. I will also use animals with impaired astrocytic ATP release to examine whether ATP released from astrocytes is necessary for in vivo hippocampal calcium wave propagation. These animals will also be used to determine if astrocytic ATP and adenosine can reduce the amount of SE-induced neuronal death in the hippocampus. [unreadable] [unreadable]